Wireless-telegraph system.



No-827,523. Y PATENIED JULY 31, 1906.

E L. DE EOEEST.

WIRELESS TELEGRAPH SYSTEM.

APPLICATION FIL ED DEO.6. 1905.

3 SHEETSSHEET 1.

No. 827,523. PATENTEDJULY 31, 1906.

- L. DE FOREST.

WIRELESS TELEGRAPH SYSTEM.

APPLICATION FILED DEO.6; 1905 s SHEETSSHEET 2.

\A/PFHESEEE:

N0. 827,523. PATENTED JULY 31, 1906.

L. DE FOREST.

WIRELESS TELEGRAPH SYSTEM.

APPLICATION FILED 1350.6,1905.

3 SHEETS-SHEET 3.

UNITED STATES LEE on FOREST, OF'NEW YORK, NY.

WIRELESS-TELEGRAPH SYSTEM.

Specification of Letters Patent.

Patented; Julyifi, 1906 Application filed December 6,1905. Serial No.290,567.

' To a It'll/717% it may concern:

. tion.

. the receiving operator at said station is 'en-,

- My invention relates td Wireless telegraphy and has for its object asystemwhich is provided with separate transmitting and receivingantennae at the same terminal station and which thereby has theadvantage that abled to cut in upon and interrupt the transmittingoperator at another station, as well as certain other advantageshereinaftei" set forth. f I

In the drawings which .accornp'a'ny and form apart of this"specification and which illustrate diagrammatically several systems iof circuits whereby my invention may be carried into effect, Figure 1represents a transmitting and receiving system and Figs. 2, 3 and 4represent receiving systems and a portion of their accompanyingtransmitting apparatus.

I shall first describe the system shown in Fig. 1 inwhich thetransmitting and receiving sets are provided with separate antennae andshall then show by reference to Figs. 2, 3 and 4 how suchconstructionenables a receiving operator tointerrupt the transmis sionfrom a distant station.

In Fig. 1, X represents the building in which the sending and receivinginstruments are located and M represents a mast, tower, or othersuitable support for the antennae. The sending-antenna A is insulated atits upper end by the insulators D and is secured by the members I and Jto the spar B which in turn is secured to the mast. The receiving-antenna A is not insulated at its upper end being conductivelyconnected to the rod J of conducting material which by me ans of thecable G passing over the pulley F is sup ported at any desired height bythe mast.

'The cable G is secured to the cleat H when n the antenna A has beenhauled up to the desired height and the lower end of said cable isconnected to earth at E.

It is preferred to give the two'a ntennae dif ferent shapes and for thispurpose the conductors of the antenna A are separated by the spreader Ka distance about ten feet apart-while those of antenna A aresepatwenty-five .feet apart.

and the insulator n.

rated the spreader K a distance of about spreaders K, K are equal inlength and many more conductors are employed in the transmitting-antennathan in: the receiving-antenna. the guys V, V, in the usual manner.

Preferably the.

The spreaders are guyed by When the circuit of the generator A is Iclosed by the key 70 the high-potential, lowfrequency current developedin the secondary ofthe transformer Q charges the con denser C and saidcondenser discharges across the gap S therebyproducing highpotential,high-frequency oscillations in the oscillation circuit C S c which, bymeans of theifisul'amr N and passes out to the earth connection Ethrough the insulator a. The'ratio of transformation, as well as theperiods of the oscillation-circuit and the antenna, may be varied by theadjustable contacts c and c, and preferably said periods are made equal.

A certain number of the wires of the rethe auto-transformer L, areconveyedsto the antenna A'Which enters the station throughceiving-antenna, herein shown as the two wires 1, 1, enter the stationthrough one of 'the'insulators N and the rest of'the wires of saidantenna enter through the other insulator N, and each set of wirestl'len passes to earth at E through the induetances L, L

By means of the variable contacts (1, d, the desired amount ofinductance may be included in the two sides 1, 1, and 2, 2, of the loopantenna A, so that the period of the latter may be madeequal to that ofthe. tuned receiving-circuit d R C which includes the receiver R, thevariable condenser C and a portion of'the -inductance L, and so thatsaid period may be made equal to that of the electromagnetic waves tobereceived. The local circuit which is connected across the terminals ofthe receiver R includes the head telephone T and potentiometer P whichregulates the potential of the battery B to be impressed upon saidreceiver.

O is a switch for connecting the two sides 1, 1, and 2, 2, of the loopantenna A to the receiving apparatus during the receipt of messages andfor disconnecting said antenna from said apparatus during thetransmission of messages.

It is not new in wireless telegraphy to employ a switch for the purposeof connecting an antenna alternately -to the transmitting and thereceiving apparatus at a station, but so far as I am aware no systemheretofore has; been devised in which separate transmitting andreceiving antennae are provided at the samestation and in which a switchis employed as above set forth. Some of the advantages of thisconstruction are that it permits the employment for transmitting andreceiving of the kind of antennae required,

difference between the point of attachment, I

of the switch to the antenna and the earth from rupturing the dielectricintervening be-- tween the switch and the receiving apparatus. In someof the commercial wirelesstelegraph stations of my construction, I havebeen able to draw a spark one foot inlength from thetransmitting-antenna, and in such case it will be obvious that in orderto make use of the same antenna for transmitting and receiving a switchfor alternately connecting said antenna to the transmitting andreceiving apparatus would have to be over one foot in length and to havea throw of over one foot. However, when a separate antenna is used forreceiving, a small, low-potential switch may be used to disconnect thereceiving apparatus'during transmission because but relatively smallpotentials are developed in such receiving-antenna by the oscillationscreated in the transmitting-antenna at the same station. In some of mystations constructed as shown in Fig. 1, the difference of potentialbetween the pointsio, 0, and the earth during the operation ofthetransmitting system is so small as to produce a spark of only one andone-half inches in length,

and hence it will be seen that the switch 0 need have a throw of butlittle longer than one and one-half inches.

Another advantage incidental to separate transmitting and receivingantennae is that thereby the receiving-operator is enabled to cut intoand interrupt the transmission from a distant station, and various meansfor accomplishing this result are shown in Figs. 2,

.3 and 4. r

In Fig. 2, a portion only of the transmittin -antenna and of thetransmitting-circuits is s own, but it is to be understood that saidantenna and circuits are arranged as shown in Fig. 1, and also that inFi s. 3 and 4, in each of which a portion only of the transmitlting-circuits is shown, said circuits also are arranged as shown inFig. 1. At points above the connections d, d, of the antennawiresl, 2,with the inductances L, L, two conductors. connect said antenna-wires totwo-pointed terminals of the anchor sparkgaps each about onesixty-fourth inch long, and the third pointed terminal of said gap isgrounded at E. A similar anchor spark-gap s has two of its membersconnected in shunt to that portion of the inductance I) which isincluded in the tuned receiving-circuit and the third member of said gap1s grounded at 6. It will now be obvious that as the oscillationscreated in thereceiving-antenna by the transmitting-antenna A are ofsufficient potential to bridge the gaps in the anchor sparkgap 8 suchoscillations will pass to earth by way of'sai'd gap andwill nottherefore affect While the gap 8 is generally sufficient, it may, as anextra precaution, sometimes be desirable to employ the gap 8, which, incase any appreciable difference of potential exists the oscillationscreating said potential to earth at e.

While, with receivers of certain types it would be possible to transmitsignals from the transmitting side of the system (shown in Fig. 2)without affecting the receiver R when the anchor spark-gaps s ands areconnected as shown, nevertheless with other and more sensitive receiversit is necessary to adopt a still further protection. Such protection iskey closes the circuit of the generator A and primary of the transformerQ, and such shuntin may be effected by connecting one termina of theshunt to the outer end of said with the other terminal f of the shuntwhen the key closes the generator-circuit at g. It will be noted thatthe anchor spark-gaps do not interfere with the reception of signalsfrom a transmitting-station because the potentials developed in. the"receiving-antenna are far too feebleto bridge said gaps, and hence,when the key is in such position that the shunt around the receiver R isopen, any signals which may be sent out from a distant station may beread by the operator at the station shown in Fig. 2, who keepsthetelephone T in position while sending.

It Will be noted that when the shunt around the receiver R is closed atf, the battery B is practically short-circuited, and, inasmuch as thesaid shunt is closed from six hundred to one thousand times a minute incommercial signaling, the battery soon runs down. In order to remedythis defect, the circuits may be arranged so that the key will openthebattery-circuit as well as shunt the receiver. One arrangementwhereby this result maybe the tuned receiving-circuit or the receiverR.-

afforded by shunting the receiver when the.

key and causing said outer end to contact gap 8, which consists of threeor more spark- -across the terminals of the 0011 L. conducts 'efiectedis shown in Fig. 3 in which for the purpose oi'illustration the receiveris shown connected in series with the antenna A and not in a tunedreceiving-circuit as in Figs. 1 and An anchor spark-gap 8, connected tothe antenna at point above the receiver and to earth at e, performs thesame function as the gap 8 of Fig. 2 performs with respect to the loopantenna shown in Fig. 2. It will be obvious that as the key k of Fig. 3is depressed, the double-pointed contact Z, which normally is held incontact with the spring h by the retractile spring j, is moved out ofcontact with h, thereby opening the circuit of the battery B, andimmediately afterward is brought into contact with the spring i, therebyclosing the shunt around the receiver R. Another way of protecting thereceiver during transmission and at the same time preventing thebatteryfrom running down by opening its circuit, is shown in Fig. 4, inwhich one terminal on of the receiver R is attached to the insulatingmember 1) which projects from the end of the key, so that when the keycloses the contact 9, the member m is moved out of contact .With theelectrolyte in which its lower end normally is immersed. of vibration ofthe member p during the operation of the key in commercial working, themember m ofthe receiver is subject to a certain amount of wear, so thatI prefer an arrangement,- such as that shown inFig. 3, in which themembers of the receiver are not subject to motion.

It is not necessary that the separate transmitting and receivingantennae at a station should be supported by the same mast for it willbe obvious that'ea'ch antenna maybe provided with a mast and that saidmasts may be separated by suflicient distance to permit of duplexworking. For example, the transmitting and receiving antennae of a sta-'tion may be separated by a substantial distance of, say, ten miles,which separation will make it possible for the receiving apparatus toreceive signals transmitted from a distant system by waves of one wavelength or frequency at the sametime that the transmitting apparatus ofsaid station is transmittingsignals by waves of different wave length orfrequency. In such case the transmitting and receiving apparatus of thestation may be connected y a pony telegraph-line so that the receivingoperator can inform the [sending operator by wire telegraph just what heis receiving.

I do not limit myself to the specific apparatus and circuits which Ihave herein described for the purpose of more fully explain- However, inview of the rapidity I claim 1. In a wireless-telegraph system, thecombination with transmitting and receiving systems at a terminalstation, of separate multiple antennae forsaid transmitting andreceiving systems, .the transmitting multiple antenna comprising alarger number of conductors than the receiving multiple antenna ,spacedthan those of the receiving-anteima, and means attuning saidtransmitting and receiving antennae to different frequencies.

2. In a wireless-telegraph system, the combination with transmitting andreceiving s ystems at a terminal station, of separate multiple antennaefor said transmitting and receiving systems, the transmitting multipleantenna comprising a larger number of con ductors than the receivingmultiple antenna.

3. In a wireless-telegraph system, a receiving-antenna, a receiverassociated therewith,

' and means associated with said antenna for protecting said receiverfrom the effects of excessive electrical potentials.

. 4. In a wireless-telegraph system, a receiving-antenna, a receiverassociated therewith, and an anchor spark gap so connected with saidantenna as to protect said recei er from the effects ofexcessivepotentials.

5. In a wireless-telegraph system, a receiving-antenna, a tunedreceiving-circuit associated therewith, a receiver connected in serieswith said tuned receiving-circuit, means associated with said antennafor protecting said receiver from the effects of excessive potentialsand other means associated with said tuned receiving-circuit forprotecting said receiver from theei'l'ec'ts of excessive potentials.

6. In a wireless-telegraph system, a transmitting system including atransmittingantenna, a receiving system including a receiving-antennaand a receiver, a transn'iittingkey associated with both systems, andmeans operated by said key for closing a circuit around said receiver toprotect the latter from the electrical efl'ects developed in saidreceiving-antenna by the oscillations created in saidtransmitting-antenna.

' 7. In a wireless-telegraph system, a receiver, a battery associatedtherewith, a transmitting-key and means for closing a circuit aroundsaid .receiver and opening the circuit of said battery'by the operationof said key. I

8. Inawirelesstelegraph system, a transmitting system including atransmitting-antenna, a receiving system including a receiving-antennaand a receiver, a transmitting-- key associated with both systems, andmeans associated with said key for protecting said receiver from theelectrical eflects developed in said receiving-antenna by theoscillations created in said transmittingantenna.

9. In a wireless-telegraph systein, a receivand having its conductorsmore closely' ing-antenna, a tuned receiving-circuit associatedtherewith, a receiver connected inse ries with said tuned receivin'gcircuit, a spark.

gap shuntedaround said receiving-circuit ceiver from the effects ofexcessivepotentials.

and connected to earth, and a spark-gap connected in shunt to saidreceiverand so constructedand arranged asto protect said re- 10.1111 awireless-telegraph system, a receiver, a spark-gap consistin of at leastthree pointed electrodes connect receiver and aconnection to. earth forone o said pointed electrodes.

11. In a wireless-telegraph system, a receiver, a spark-gap connected inshunt thereto, a transmitting-key and means for closing a circuit aroundsaid receiver by the opera- I tion of said key,

. 12. In a wireless-telegraph:system a receiving-antenna,' a receiverassociated therewith, an, anchor spark-gap so connectednto said antennaas to protectsaid receiver from the effects of excessive potentials, atransmitting key and means'for further protecting said receiver by theoperation of said key. a

13. In a wireless-telegraph system,-a rein shunt to said -with'said'receiver'for protecting said receiver from the effects of excessivepotentials, a transmitting-key, and means for further protecting saidreceiver by the operation of said key.

14. In a wireless-telegraphvsystem, areceiv-ing-antenna, a receiverassociated therewith, means associated withsaidantenna for protectingsaid reeeiverfrom the efiects of- -.excess1ve potentials, othermeansassociated with said receiverfor protecting said receiver from theeflects-of excessive potentials,a transmittin key, and means for closinga-circuit 'aroun said receiver by the operation of said .key.

. In testimony whereof 'I havehereunto subscribed my name-this 29th'dayof November,

1905; LEE DE "FOREST.

Witnesses: I

. PHILIP FARNSWORTH,

A. E. PARKER.

